Cast components often require repair during their life. Because of the physical characteristics of cast materials, it is difficult and time consuming to repair cast components. Typically repairs to castings involve removing damaged portions of the casting through machining, and subsequently rebuilding the damaged area by welding.
One example of a component that is susceptible to damage is the cylinder head of an internal combustion engine. Because of repeated heating and cooling of the engine, the cylinder heads often develop cracks near openings, such as valve seats, fuel injector bores, and exhaust ports. Another problem associated with cylinder heads is warping. When warped, the bottom surface of the head becomes uneven and does not seal properly. Some warped cylinder heads can be milled until the fireside surface is again flat. However, milling the surface reduces the thickness of the head, making the head more susceptible to future operating damage. Heads that can't be milled flat are typically scrapped. Current processes are unable to repair warped heads by building up the surface thickness.
One example of repairing a casting is discussed in U.S. Pat. No. 4,918,805 assigned to General Motors Corporation. This patent describes a method for repairing a cylinder head of an internal combustion engine by welding. Grinding or a similar machining process removes the damaged portion of the cylinder head. After the damaged material is removed it is replaced using a welding process. A drawback to using this or a similar process is that it is labor intensive to repair even a single crack. Many damaged heads have multiple cracks to be repaired. Each damaged portion being repaired must be removed, the entire head preheated, and then welded. During welding, the temperature of the surrounding area must be elevated and maintained high enough to permit sufficient bonding of the parent and filler material. After welding, the bead must be machined to original manufacturer's specifications. The welding repair process may take hours per cylinder head.
The present disclosure is directed to overcoming one more of the problems set forth above.